A compact low-profile dual-band Circularly Polarized (CP) microstrip antenna is proposed for the BeiDou Navigation Satellite System (BDS). To achieve dual-band functionality, a single-layer multimode design is employed, incorporating F-, L-, and T-shaped slots at the corners for CP performance. Additionally, a Defected Ground Structure (DGS) is implemented to further enhance the antenna’s efficiency. A detailed parameter analysis is conducted to optimize the antenna’s size and performance balance. After optimization, the final dimensions of the antenna are minimized while still meeting the design requirements. The prototype of the optimized antenna is fabricated and tested, demonstrating coverage of frequency bands from 1.182 GHz to 1.217 GHz and 1.547 GHz to 1.569 GHz. The antenna effectively supports dual-band CP for B1I and B2b frequency bands. A performance metric, the Ratio of relative Bandwidth to Volume (RBV), is introduced to evaluate the antenna’s efficiency. Compared to similar designs, the proposed antenna offers a smaller size without sacrificing performance, making it well-suited for BDS airborne applications.

A two-stage degradation model considering degradation rate interactions is proposed for the degradation of binary load-sharing components in highly complex airborne systems affected by degradation process interactions and load sharing. Firstly, a two-component degradation dependence characterization method based on degradation rate interaction is investigated to establish a two-component degradation correlation model without considering the influence of load sharing. Secondly, considering the influence of load sharing on degradation rate, the system degradation process is divided into two stages with a component failure as a variable point, and a two-component degradation correlation model with the influence of load sharing is constructed. The model parameters are estimated using the great likelihood estimation method, and the reliability model and the remaining life model of the system are constructed. Finally, taking an aviation component as an example, the reliability calculation of the load-sharing system related to binary degradation is carried out, and the proposed method provides support for the reliability analysis of the degradation and failure of binary load-sharing components of complex systems.